Display device

ABSTRACT

An air duct plate is provided on the back of a substrate on the surface of which a light emitting element group for display as well as an integrated circuit are disposed. A fan acts to send air into a space surrounded by a case body extending over and around the air duct plate and the air duct plate. A plurality of openings acting to blow a cooling air generated by the fan to a predetermined portion of the substrate are formed in the air duct plate.

TECHNICAL FIELD

The present invention relates to a display device causing a lightemitting element group to emit light to make a display and, moreparticularly, to a display device that can suppress the rise oftemperature resulted from heat generation accompanied by light emissionof a light emitting element group as well as temperature distribution.

BACKGROUND ART

Recently, display devices using a plasma display, a liquid crystaldisplay, a field emission display and the like including a lightemitting diode (hereinafter, it is abbreviated as LED (Light EmittingDiode)) have been generally known and have been widely employed togetherwith those using a conventional CRT (Cathode Ray Tube), a discharge tubeor the like, or in substitution for them.

However, in these display devices, a conversion efficiency of light islow, and, for example, as to LED elements, it is about 10% and mostsupplied power is to be converted to heat. Furthermore, the rise intemperature of the above-mentioned elements further decreases theconversion efficiency of light, thus to be the cause of reduction inreliability of elements and uneven brightness. In particular, in thecase that elements of displaying colors (for example, elements ofdisplaying a red color, blue color and green color) have different lightconversion efficiencies, this fact is to be a primary factor ofgeneration of irregular colors, and a problem exits in, e.g., thereduction in quality of images.

In the case of a display device using a light emitting element such asLED element, being different from the one that uses a normal CRT and thelike, light emitting sources, that is, light emitting elements of whichtemperatures should be uniform are arranged normally at regularintervals on the entire surface of a display device. In addition,integrated circuits, for example, a driver IC, a logic IC, an FET, and aclock IC necessary for controlling the light emission of LED elementsare a source of heat generation. Since these integrated circuits aredisposed on a substrate avoiding an LED element, an interface, acapacitor and the like, they cannot be arranged at regular intervals,which will be the factor of generation of temperature distributionbetween the LED elements.

Therefore, it is required to suppress the rise in temperature of theelements and the temperature distribution between the elements with theuse of some cooling unit. Conventionally, to cope with this, an attempthas been proposed, and in which a ventilation hole is formed in adisplay panel part that is provided to mold the LED so as to get throughfrom its front face to its back face; as well as a cooling air havingbeen taken in from outside using a fan cools a cell substratefunctioning to drive the LED, and thereafter the cooling air is sent tothe front face on the display panel side through the above-mentionedventilation path, whereby heat having been radiated from the displaycell is discharged to the outside. (For Example, Refer to PatentDocument 1.)

In addition, another cooling system of a display has been proposed, andin which a partition plate is disposed in the proximity of the back of alight guide, whereby a channel of fluid that is adjacent to the back ofthe light guide is formed. (For example, refer to Patent Document 2.)

Patent Document 1: Japanese Patent Publication (unexamined) No.293540/1998

Patent Document 2: Japanese Patent Publication (unexamined) No.76286/2003

DISCLOSURE OF INVENTION

Problems to be Solved by the Invention

In the display device disclosed in the mentioned Patent Document 1, asdescribed above, since a cell substrate functioning to drive an LED isdifferent from an LED mount substrate, it is certain that there is noinfluence of temperature distribution as a result of heat generation ofthe LED drive elements, but a plurality of substrates results in theincrease in cost. Moreover, since a ventilation hole is formed so as toget through a display unit from front face to back face, it is certainthat a cooling capacity with respect to a substrate is surely improvedto some extent, but a ventilation hole needs to be formed in the displayunit, resulting in increased manufacturing cost and exceedinglycomplicated structure. Furthermore, since a mold member is disposedbetween an LED mount substrate and a cooling air passing through theventilation hole, to act as a thermal resistance, resulting in lesscooling efficiency than it should be.

In addition, in the cooling system of the display disclosed in mentionedPatent Document 2, an outside air that has been sucked using a pumpingfan just flows upwards in a cooling chamber defined by a partition wall.Thus, it is certain that the back of a light guide can be cooled, but inthe case that a heat generation part such as an integrated circuit isdisposed at a specified portion on a substrate, uniform temperaturedistribution cannot be achieved.

The present invention was made in view of the mentioned technicalproblems, and has a basic object of providing a display device using alight emitting element capable of cooling a substrate where lightemitting elements are arranged comparatively uniformly as well asefficiently without incurring excessive rise in cost and complicatedstructure.

Means of Solution to the Problem

A display device according to the invention includes: a substrate on thesurface of which a light emitting element group for display as well asan integrated circuit are disposed; an air duct plate disposed on thebackside of the mentioned substrate at a predetermined distance from thesubstrate; a case body extending over and around the mentioned air ductplate; and a fan sending an air into a space that is surrounded by thementioned case body and air duct plate, in which a plurality of openingsacting to blow a cooling air having been generated by the mentioned fanto a predetermined portion on the side of the mentioned substrate areformed in the mentioned air duct plate.

ADVANTAGES OF THE INVENTION

According to the invention, a cooling air having been sent by the faninto the space that is surrounded by the case body and the air ductplate can be made to pass through the openings formed in the air ductplate in a region covered with the case body to be blown to thesubstrate. At the point to which this cooling air has been blown, thecooling efficiency is locally increased. Therefore, by forming eachopening at a position corresponding to a local heat generation source(integrated circuit) or to a region of stagnation of a cooling air(e.g., axial center of fan), temperature distribution can be reduced.

As a result, a light emitting element group and an integrated circuit onthe substrate can be cooled efficiently as well as uniformly, and thusit is possible to obtain a highly reliable display device of less unevenbrightness and irregular colors. In this manner, a comparatively simpleconstruction of just providing an air duct plate provided with openingsbetween the substrate and the fan is sufficient, so that there is noneed of excessively complicated structure or rise in cost as in theprior arts.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an air duct plate in a display deviceaccording to a first embodiment of the present invention.

FIG. 2 is a sectional view of a display device according to a firstembodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

A preferred embodiment according to the present invention is hereinafterdescribed in detail referring to the accompanying drawings. FIG. 1 is aschematic diagram of a display device according to a first embodiment ofthe present invention viewed from backside. And FIG. 2 is a diagramschematically illustrating a cross section taken along the line A-A ofFIG. 1. A plurality of such display units as illustrated in the drawingsare arranged lengthwise and crosswise to form a display device of alarge screen as a whole. Incidentally, although in FIG. 2, there is nofan present in the cross section taken along the line A-A, for reasonsof convenience of explanation, it is illustrated at a position beingprojected on the cross section taken along the line A-A.

In the drawings, reference numeral 1 designates a substrate supported bya substrate support 2 on the surface side of a display device, numeral 3designates, for example, an LED element group of a plurality of LEDelements arranged lengthwise and crosswise on the surface of theabove-mentioned substrate 1, numeral 4 designates an integrated circuitthat is likewise disposed on the back of the above-mentioned substrate 1and that makes, e.g., a drive control of the above-mentioned LED element3, numeral 5 designates a fan that is disposed on a back of an air ductplate 6. The air duct plate 6 is disposed in a space between theabove-mentioned substrate 1 and the fan 5 at a predetermined distancefrom mentioned substrate, numeral 7 designates a case body extendingover and around the above-mentioned air duct plate 6, numeral 8designates a cooling air outlet, and numerals 9 and 10 designateinterface connectors that are formed on the substrate 1 and connected toan external power source and an external controller via theabove-mentioned cooling air outlet 8, and in which numeral 9 is a powersource interface connector and numeral 10 is a controlling interfaceconnector. Numerals 11 a and 11 b designate openings formed in theabove-mentioned air duct plate 6, and in which numeral 11 a is anopening formed, for example, above the integrated circuit 4 and numeral11 b is an opening formed right below the above-mentioned fan 5respectively.

The amount of heat generation at the substrate 1 is a superposed amountof the heat generation to be generated from the LED element group 3 thatis arranged at regular intervals and the heat generation to be generatedlocally at the integrated circuit 4 and the like. Accordingly, it isnecessary to cool the entire substrate 1 and to locally increase thecooling efficiency in the region of the integrated circuit 4 and thelike. Incidentally, although the air duct plate 6 is attached to thesubstrate support 2 via the case body 7 in the above-mentionedembodiment, it is possible to form an integral structure of the air ductplate 6 and the case body 7. Furthermore, the cooling air outlet 8 isfabricated by forming the openings in the air duct plate 6, thusachieving a simple structure.

In the above-mentioned construction, a cooling air 13 having been sentinto a space 12 that is surrounded by the case body 7 and the air ductplate 6 using the fan 5 is blown to the substrate 1 where the LEDelement group 3 is arranged at regular intervals through the openings 11a, 11 b formed in the air duct plate 6, and thereafter passes through anair flow path 14 that is formed between the substrate 1 and the air ductplate 6 to be discharged from the cooling air outlet 8 to the outside.

In this embodiment, the opening 11 a is formed at a positioncorresponding to the integrated circuit of the substrate. The coolingair 13 is blown through the opening 11 a to the integrated circuit 4that is disposed on the substrate 1 and the peripheral portion of thesubstrate. Since cooling efficiency is improved at the points where thecooling air 13 is impinged on the substrate, the cooling efficiency inregions of the integrated circuit 4 and the like can be locallyincreased. In addition, the cooling air 13 having been blown passesthrough the air flow path 14 between the substrate 1 and the air ductplate 6 to be discharged from the cooling air outlet 8, so that theentire substrate 1 can be cooled. Thus, by properly adjusting theposition and the size of the openings 11 a, 11 b, the temperaturedistribution on the substrate is reduced to a minimum as well as highercooling efficiency on the substrate 1 can be achieved.

Further, in this embodiment, at a position corresponding to the centerportion of the fan 5, the opening 11 b of the air duct plate is formed.In the axial flow fan 5, no air flows in its axial portion, andtherefore the portion right below the axis of the fan 5 becomes astagnation point. On the other hand, since the LED element group 3 isarranged at regular intervals on the substrate 1, the portion rightbelow the fan needs to be cooled.

Owing to the construction illustrated in this embodiment and by properlyadjusting the size of the openings 11, an internal pressure in the space12 covered with the case body 7 and the air duct plate 6 can beincreased, and thus the cooling air 13 can be made to pass through theopening 11. Incidentally, since the volume of air is decreased as theinternal pressure is increased, the size of the openings 11 needs to beproperly adjusted.

Furthermore, for example, there are some cases that a capacitor and thelike, of which heat generation is relatively small but which is anobstacle to the flow of cooling air, are disposed on the substrate 1,whereby the stagnation of an air flow is generated and a temperaturelocally rises. Even in such cases, by provision of an opening above thestagnation point of an air flow, a cooling air is allowed to flow in thestagnation region, and uniform temperature distribution can be achieved.

Further, in this embodiment, the size of the opening 11 a of the airduct plate in the region covered with the case body 7 is made to belarger than that of the integrated circuit 4 of the substrate 1 to coolthe substrate at the peripheral portion of the integrated circuit 4.Since most heat having been generated at the integrated circuit isradiated from the substrate via a lead, a cooling air is not blown to acase (frame) of the integrated circuit, but to the substrate at theperipheral portion of the integrated circuit, whereby the coolingefficiency is locally increased. In addition, although the integratedcircuit 4 is generally shaped to be rectangular, in view of easymachining, it is shaped to be circular in this embodiment.

As described above, according to the embodiment of the invention, theposition of the openings 11 a, 11 b to be formed in the air duct plate 6can be arbitrarily selected, so that it is possible to design an airflow path without restraints in accordance with the elements arranged onthe substrate 1 to be used. Furthermore, points of local heat generationcan be cooled using impinging jets of high cooling efficiency, and thusit is possible to uniform the temperature distribution on the substrate,that is, the temperature distribution of the LED elements. Consequently,it comes to be possible to manufacture a display device having highreliability and high image quality of low color irregularities withoutexcessively complicated structure and rise in cost.

1. A display device comprising: a substrate including surfaces on whicha light emitting element group for display as well as an integratedcircuit are disposed; an air duct plate disposed on the backside of saidsubstrate at a predetermined distance from the substrate; a case bodyextending over and around said air duct plate; and a fan sending airinto a space that is surrounded by said case body and air duct plate,wherein a plurality of openings acting to blow cooling air generated bysaid fan to a predetermined portion of said substrate are formed in saidair duct plate.
 2. The display device according to claim 1, wherein saidair duct plate openings are formed at positions corresponding to anintegrated circuit of the substrate.
 3. The display device according toclaim 1, wherein said air duct plate openings are formed at positionscorresponding to a center portion of the fan.
 4. The display deviceaccording to claim 1, wherein size of said air duct plate openings islarger than that of the integrated circuit of the substrate.
 5. Thedisplay device according to claim 1, wherein said air duct plateopenings have a circular shape.
 6. A display device comprising: asubstrate on which a light emitting element group for display as well asan integrated circuit are disposed; an air duct plate disposed on abackside of said substrate at a predetermined distance from thesubstrate; a case body covering at least a part of said air duct plate;and a fan that is disposed on a back of said air duct plate to send airinto a space surrounded by said case body and air duct plate, wherein aplurality of openings acting to blow cooling air generated by said fanto a predetermined portion of said substrate are formed in said air ductplate; and wherein said cooling air having impinged on the back of saidair duct plate through said fan is made to pass through said openings tobe blown to said substrate, and thereafter discharged from the back ofsaid air duct plate.
 7. The display device according to claim 6, whereinat least a part of said air duct plate openings is formed at a positioncorresponding to an integrated circuit of the substrate.
 8. The displaydevice according to claim 6, wherein size of said air duct plateopenings is larger than that of the integrated circuit of the substrate.9. The display device according to claim 6, wherein said air duct plateopenings have a circular shape.
 10. The display device according toclaim 7, wherein the size of said air duct plate openings is larger thanthat of the integrated circuit of the substrate.
 11. The display deviceaccording to claim 7, wherein said air duct plate openings have acircular shape.
 12. A display device comprising: a substrate on which alight emitting element group for display as well as an integratedcircuit are disposed; an air duct plate disposed on a backside of saidsubstrate at a predetermined distance from the substrate; a case bodycovering at least a part of said air duct plate; and a fan that isdisposed on a back of said air duct plate to send air into a spacesurrounded by said case body and air duct plate, wherein a plurality ofopenings acting to blow cooling air generated by said fan to apredetermined portion of said substrate are formed in said air ductplate; and wherein at least a part of said air duct plate openings isformed at a position corresponding to a center portion of the fan. 13.The display device according to claim 12, wherein the size of said airduct plate openings is larger than that of the integrated circuit of thesubstrate.
 14. The display device according to claim 12, wherein saidair duct plate openings have a circular shape.